Return bend clamp block



Dec. 24, 1940. s. P. WYNN RETURN BEND CLAMP BLOCK Filed March 28, 1940 2 Sheets-Sheet l INVENTOR. JYO VEY PAW/ 6.5 WY/V/V.

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A ATTORNEY.

Dec.24, 1940. s. P. WYNN 2 2,225,760

RETURN BEND CLAMP BLOCK Filed March 28, 1940 2 Sheets-Sheet 2 INVENTOR. S YOWY /e/lvcz w /v/v.

ATTORNEY.

Patented Dec. 24, 1940 UNITED iSTAT-E pRETURN BEND CLAMPBLOCK .Sydney Prince Wynn, Bowdon,--Altrincham, England, assignor to The New York, N. Y.

Superheater 1. Company,

Application March 28, 1940, Serial No. 327,873

' In Great Britain-May 9 19 38 6 Claims. (01.. 25.7?255) is also detachably connected another tube,

This invention relates to tubular'heat exchange -apparatus of the kind comprising serpentine units built up from lengths of tubing connectedby removable return bends. Whilst the invention is Y more particularly concerned with boiler economisers; heat exchange apparatus embodying the; invention may be employed for other purposes Sl1Ch,fOl example, as stills for treating oil.

Where the fluid flowing through the units of theapparatus is of such a nature that fouling of thebores of the tubes is to be expected, it is essential that provision be made for inspecting the bores of the tubes and cleaning the sameand also forthe ready removal of a tube requiringto be removed; or to receive treatment which cannot be effectedwith the tube in situ. For this reason economisersand other tubular heat'exchange apparatus have been constructed with removable return bends or equivalent fittings, enabling the constituent tube lengths of the serpentine units to be disconnected from each other andremoved, and in some'cases the arrangements have been such as to permit inspection of the bores of the tubes. The present invention has for its-object to provide an improved heat exchange apparatus in which each serpentine elementor unit shall be constituted by a plurality of tubes'connected at opposite ends to return bendsb'y-r-adily break- -able joints, with the said bends forming, it may be. walls of the passage or fluid path for the external fluid, the apparatus being such that individual tubes of the element or unit may be inspected and/or cleaned in situ 'or be-removed I without removing any other tube of the element 1 or unit. I

- It is a further objectofthe inventionv to pro- 1 vide a heat exchange apparatus of the kind. with which the invention is concerned in which the individual tubes of each serpe'ntineunit are con nected to their respective return bends by joints comprising clamp-blocks which, where thetubes are disposed horizontally or at a small inclinationto the horizontal, constitute means for supporting and spacing the tubes whilst being at the same timesuch as to permitready removal of any individual tube without removal" of-the clamp block from its tube. supporting position.

The present invention consists essentially in a serpentine. unit or element for tubular heat exchange apparatus; such element being built up of lengths of tubing connectedby removable return 'bends, wherein2 each element 1 comprises a plurality ofzstraight tubes each end of each ofzwhich tubes is detachably'conn'ected to a return bend to endsJa'nd a clamp block as shown inTFig. 3, one

of the studs of the clamp'with its nut also ap-" 2 pearing in the figure.

Fig. 5 is a front view of an assembly of four returnbends and clamps with two of the eight sition, parts of said boxes being broken away to illustrate clearly provisions, hereinafter described, which enable a tube to be withdrawn without disturbing the clamping blocks.

'joined by means shown in the preceding figures? the tubesfwhich may be considered as forming .COIlStii-tllt nected. ateachend to return bendsZ bymeans of 55 the tube ends being connected to the respective returnbe'ndsby slotted clamp blocks adapted to engageabutinents-on the tubes near their ends and screw devices extending throughthe return 5 bends, the clamp blocks at the respective ends of the group of tubes being juxtaposed'with their edges in contact and determining the spacing of the tubes'of theapparatus, and the slots in the assembledblocks, and it may be portions cut away 10 irom said blocks, permitting the abutments on v the tubes to pass through the blocks and any tube t0 be withdrawn without disturbing any other tube or-any; clamp block.

-In theacoompanying drawings:

Figs. land 2 are front and back views of a -return bend for. use in 'anembodiment of the invention.

5 Fig.3 is'a-front view of aclamp block for use in association with a return bend according in one embodiment of the invention.

'= Fig. 4 is a s'ectional'view of an assembly of a return bend as shown in Figs. 1 and 2, two tube tubes to be'connected to the return bends in po- Fig. 6 is a side View of an assembly of tubes an economiser, usually would be of much greater length proportionately to the return bends and clamp blocks than those shown, which have been reduced in length for convenience of illustration, and some constructional details have been omitted, so that to. some extent the figure must be considered as being diagrammatic only. .Fig. '7 is a plan of a portion of the tube assemb-ly shown in Fig. 6, and

ThFig. 8 is afront-view of an alternative form of .clam'pb-lock' according to the invention.

1; Fig. 9 is a plan view illustrating an arrangement where several clamp blocks for tubes disuposed in a parallel rows' are combined to form a single clamp bar.

."nReferring to the drawings, each serpentine element ornunitof the heat exchange apparatus is ed by-aiplurality of straight tubes l conslotted clamp blocks 3 and studs 4 with nuts 5, the end portions of the tubes I being shaped to have jointing contact with tube seats or jointing surfaces at apertures in the return bends 2, and the clamps 3 being constructed to permit the tubes l to be removed without disturbing any clamp. The return bends are juxtaposed, as shown in Fig. 5, and preferably suitable packing material (not shown) is interposed between the opposed edges or surfaces of adjacent return bends to prevent leakage of the external fluid between such surfaces.

As the heat exchange apparatus according to this invention is more particularly intended for use as a boiler economiser, an embodiment of the invention has been selected for illustration which is suitable forsuch use and will now be fully described with reference to the drawings.

In the selected embodiment of the invention, it may be assumed that the tubes I of the economiser mainly are disposed horizontally across the gas passage but some are at a relatively slight. The economiser would; comprise a suitable number of serpentine units.

incline to the horizontal.

and each unit would in turn consist of anappropriate number of straight tubes connected in series by return bends at opposite ends of the tubes. A complete unit is shown in Figs. 6 and '7,

I being made up of sixteen tubes, and at side of the gas passage eight return bends with their asso- I ciated clamps. The number of tubes may be greater or less as desired. Each return bend 2 consists of a rectangular block of suitable thickness adapted to be arranged on edge, to one of the vertical faces of which block two tubes l are connected. With its axis parallel to said vertical face of the block, a blind hole 6 is drilled in the block, its open end being plugged at 1, and two holes 8 are drilled from the jointing face of the block to break into the said blind hole 6. At each end of a tube I a spherical jointing surface 9 is formed, and adjacent thereto an abutment l0,

1 face, is provided on the tube I.

apertures in the junction boxes are coned as at around the studs 4, permit fluid-tight joints to be having a spherical or other suitably shaped sur- Thejointing II to receive the spherical jointing surfaces 9 on the tube. For eachjunction box 2 a clamp block or dog 3 is provided. In the construction shown in Figs. 3, 4 and 5,'each clamp block has slots surfaces H of the return bends. The spherical surfaces on the tube ends, abutments IE! and washers l5, and the appropriately shaped seats for these parts, together with the clearance made and maintained between the tubes 1 and the return bends 2 notwithstanding that the axes of the tubes are slightly inclined to the axial centre lines of the holes 8, and/ or the plane of the block 3 is slightly inclined to the plane of the respective return bend 2. The clamp blocks or dogs 3 are juxtaposed and portions of each block contact with the adjacent blocks so that not only do the blocks determine the spacing of the tubes but the lower'blocks support those above. Portions are cut away at Hi from each block'and the open mouths of the slots l2 are splayed at H so that there obtains between opposed tube slots l2 of adjacent blocks 3, an enlarged slot or opening l8, Fig. 5, of sufiicient width and length to permit the abutment III on a tube to pass therethrough when the appropriate return bends 2 have been removed and such tube has been moved out of portion of a slot to be withdrawn therethrough.

When it is desired to remove a tube, the appropriate nuts are removed from the studs of the respective clamp blocks at each end of the tube and the corresponding return bends are removed. The tube is then moved into the space I80 in its clamp block, when it is free to be withdrawn. The construction of block shown in Fig. 8 has the advantage that a tube can be removed by detaching and removing only two return bends, one at each end of the tube; with the construction of block shown in Fig. 3 to remove the first tube of a group four return bends must be removed at each end toexpose the appropriate two spaces !8 and permit the tube to be moved thereinto, after which adjacent return bends are removed as required to expose the respective spaces I8 for the removal of the adjacent tubes. Blocks according to Fig. 3, however, have an advantage as compared with those according to Fig. 8 in that they permit a closer pitching of the tubes.

It will be appreciated that by removing the return bends the tubes can be inspected and cleaned internally in situ, and the jointing surfaces examined. For external cleaning or a more thorough examination the tubes would be with drawn.

In order to prevent access of the combustion gases, in the case of a boiler economiser, to the joints of the tubes with the return bends, suitable protecting rings l9, Fig. 4, may be provided between-the abutment ID on a tube end and the opposed surface of the return bend, the rings being, for example, of copper and asbestos. Conveniently a single strip of asbestos-copper material may be employed to provide the protective rings or sheaths of both tubes associated with a return bend, the parts of the strip being brought together between the tubes and secured by a rivet or rivets. A ring or sheath of similar material may be provided around each stud for protective purposes. With return bends constructed as shown in Figs. 1, 2 and 5, or Fig. 8, and arranged as shown in Fig. 6, the two tubes associated with a return bend have their ends at different levels as shown, and the protective rings or sheaths of such pair of tubes may be formed as one unit, the unit so formed serving to hold the ends of the tubes in position in the clamp blockwhen the return bend has been removed.

The invention is not confined to heat exchange apparatus in which the tubes are arranged horizontally or at a relatively small inclination to the horizontal and, if desired, it may be applied to apparatus in which the tubes are vertical. In

- this case, suitable means would be provided for supporting the tubes. For example, instead of the element or unit being provided at both its upper and lower sides with a plurality of clamp blocks, each appertaining to two tubes only, the lower clamp blocks may be retained, and there be substituted for the upper clamp blocks a single clamp bar 23 as shown in Fig. 9 supported at its ends and/or at points along its length, as by suspension rods 24, in such a manner as to constitute a support for the element, the bar bein slotted at intervals as requiredfor engagement with the abutments on the tubes. Clamp bars of this form might be employed with elements whose tube runs are horizontal, but the clamp block arrangement previously described is considered preferable with tubes so arranged.

Whilst in the foregoing description single tubes have been referred to, it is within the scope of the invention to employ tubes which are bifurcated between the clamp blocks in which case each bifurcated tube would preferably be constructed with the union portion at one end aligned, or approximately aligned, with one leg of the tube, and the union portion at the other end aligned, or approximately aligned, with the other leg of the tube as described in Patent No. 1,924,900, in order to provide for ready inspection of the respective legs of the tube. The invention is also applicable where the tube unit of an element is constituted by a group or bundle of three or more tube lengths united at each end into a single end portion or union, the cut away portions of the clamp blocks being such as to provide for the passage of the tube units in withdrawing a unit from the apparatus.

As will be understood, in a heat exchanger embodying the invention expansion of the tubes will take place, the amount of such expansion varying in the different tubes of a serpentine unit. In embodiments of the invention in which each clamp block is associated with two tubes only expansion of individual tubes can take place as each clamp block can move independently of neighbouring blocks, and where the tubes are disposed horizontally the slight sliding movement, in a direction longitudinally of the tubes, of a block on the block immediately below, which takes place when differential expansion of the tubes occurs, can be facilitated by machining away a portion of the lower and/or upper edge surface of each block between its ends as shown in dotted lines at 28, Figs. 3 and 8, to reduce the area of frictional contact between the blocks.

I claim:

1. A serpentine unit or element for tubular heat exchange apparatus, such element being built up of lengths of tubing connected by removable return bends, wherein each element comprises a plurality of straight tubes each end of each of which tubes is detachably connected to a return bend to which is also detachably connected another tube, the tube ends being connected to the respective return bends by slotted clamp blocks adapted to engage abutments on the tubes near their ends and screw devices extending through the return bends, the clamp blocks at the respective ends of the group of tubes being juxtaposed with their edges in contact and determining the spacing of the tubes of the apparatus, and the slots in the assembled blocks permitting the abutments on the tubes to pass through the blocks and any tube to be withdrawn without disturbing any other tube or any clamp block.

2. A heat exchange element as claimed in claim 1, wherein each slot in each block extends to the edge of the block and has its mouth or entrance enlarged and opposes the mouth of a slot in an adjacent block, portions of two other adjacent blocks being cut away to provide a space Whose dimensions permit an abutment on a tube after removal of the appropriate return bends, to pass through the space when the tube has been removed from its normal position in the slot in a block into the said space, thereby permitting tubes to be removed without disturbing the clamp blocks.

3. A heat exchange element as claimed in claim 1, wherein a single closed-ended slot is formed through a clamp block, the tubes normally lying at the opposite ends of the slot, and the intermediate region of each slot being enlarged to permit an abutment on a tube when the appropriate return bends have been detached and removed and when the tube is moved into such region, to pass through the block and the tube to be withdrawn from the apparatus through the block without disturbing any of the clamp blocks.

4. A heat exchange element as claimed in claim 1, having a plurality of clamp blocks at one side or end of the element and in lieu thereof at the other side or end of the element a slotted bar engaging the abutments at such side or end of the element of all the tubes comprised therein, said bar, where the tubes are disposed vertically, being supported at appropriate points in its length and constituting a support for the tubes.

5. A heat exchanger having elements as claimed in claim 1 with the element tubes disposed horizontally or at a small inclination to the horizontal, wherein the clamp blocks of the exchanger are arranged on edge and superposed with the lower blocks supporting those above.

6. A heat exchange element as claimed in claim 1 wherein to facilitate differential expansion of the tubes the lower and/or upper edge surface of each block is machined away between its ends.

SYDNEY PRINCE WYNN. 

